1. Field of the Invention
This invention relates to spandex fibers which are detectable by means of X-ray and a method for producing them.
2. Description of the Prior Art
Spandex fibers made from long chain synthetic polymers comprising at least 85% segmented polyurethanes are well known. Such spandex fibers have been found to be useful as retractile elements in the preparation of artificial ligaments for use in surgical replacement therapy as described in U.S. Pat. No. 4,610,688 issued Sep. 9, 1986 on the application of Silvestrini et al. The use of an X-ray detectable spandex fiber would be advantageous in such applications so that the placement of an implanted ligament containing such fibers could be monitored by radiographic techniques.
There now has been discovered through the process of this invention an X-ray detectable spandex fiber that has the elongation and flex life required for artificial ligaments and other applications where these qualities of the spandex fiber must be retained.
U.S. Pat. No. 4,185,626 issued Jan. 29, 1980 on the application of Jones et al. discloses an X-ray detectable filament of an elastomeric, nonpolyurethane material. Jones et al. teaches that the filament incorporates throughout its length a continuous reinforcing thread as the filament is heavily loaded with an X-ray detectable filler which may give rise to breaks during stretching and may even permit the filler to disperse. A non toxic element of atomic weight above 100, or one of its compounds such as barium sulfate is disclosed by Jones et al. as an X-ray opaque filler material.